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Show 260 CHEYENNE PASS. crossing the hills and hollows formed bj the drains coming from them, the undulations, however, being quite gentle. On our right, about two miles distant, stretched a high table ridge, or plateau, rising one hundred and fifty or two hundred feet, its western escarpments abrupt, nearly vertical, and capped in this vicinity by argil* laceous limestone and sandstones, with occasional strata of pudding- stone. Between this plateau on our right and the Black Hills on our left, there is a marked depression or valley, averaging about four miles in width, and which appears to have been cut out by the violent action of an immense body of water flowing in a northern direction. The valley extends along the base of the . Black Hills, from where we first descended their eastern slope, to the Chugwater; the range of marly hills reaching, as our guides told us, to the Platte, in the vicinity of Scott's Bluffs, and thence to " Chimney Rock" and " The Court- house." The formation appeared to be the same as that observed at those localities. The depression thus formed is called the " Cheyenne Pass," from the constant use made of it by that tribe in their migrations to and from the Platte. From the red caflon of Crow Creek to some distance down the Chugwater, a range of lower hills, apparently of lime and sandstone of different colours and qualities, occurs, flanking and following the general direction of the main back- bone of the Black Hills. Through these, the numerous streams which take their rise in the ridge beyond have forced a passage in deep, narrow, and rugged caflons, and, after crossing the Cheyenne Pass, have broken through the marly plateau on our right, in their passage through the plains to the eastward into the North and South Forks of the Platte. Following the Cheyenne Pass nine miles from our morning's camp, after crossing the north or main fork of Crow Creek, some two miles below its caflon, we struck upon the southern branch of Lodge- pole Creek, and, five miles beyond, halted to noon upon, Bear Creek, one of its tributaries, where a meridian observation gave for the latitude 41° 21' 45". 7. We had now reached the heads of the stream, which I had previously determined to follow to its confluence with the South Fork of the Platte. As we could expect to receive no addition to our supplies before reaching Fort Kearny, I despatched an express to Fort Laramie for such articles of food as were required, and occupied the interval until their return in making an examination of the eastern base of the Black Hills to the northward. |